I would like Google Science Journal to be able to record sensor data from my Puck.je over BLE.

Can you point me to an example that would be relevant please?

Here are the details, from a user who had a similar problem, visa vi, the Micro:Bit

"As I understand it the Science Journal app is looking for Bluetooth advertising a service with the UUID "555a0001-0aaa-467a-9538-01f0652c74e8" and sends the value of the sensor on a characteristic with the UUID of "555a0003-0aaa-467a-9538-01f0652c74e8.

I'm looking to translate that logic to Espruino code. I guess temperature would be good place to start. Note, I'm not trying to create a BLE temperature sensor with the expected temp sensor profile, but rather this particualr flavor the the Science Journal requires.

Works like a champ, I just dumped the latest appropriate binary from the Espruino repo onto an Nordic DK-52 and then used the Windows 10 binary IDE to upload the code you suggested in your kind response.

Now I need to think about what I2C peripherals would make sense to evaluate...

Thanks again.

Ps. Your software solution was in conclusion, hand's down the easiest! I tried quite a list of technologies.